Cholesterol. You have heard it is "bad for you," but why? Where does it come from? Does it do anything besides clog your arteries?
What Is Cholesterol?
Cholesterol has quite a bad reputation. Much of it is not deserved. Cholesterol is a vital component of all cell membranes. It protects nerve cells and is the backbone for many hormones—among them cortisol, estrogen, progesterone, and testosterone. It is also used to make vitamin D and bile, a substance that helps digest fat.
Unfortunately, too high a concentration of cholesterol in the blood is associated with an increased risk of heart disease.
Coronary artery disease affects millions of Americans. High cholesterol
is one of many risk factors for developing heart disease.
Where Does Cholesterol Come From?
Your body makes all the cholesterol you need. It is made in the liver. Cholesterol is also found in foods. Dietary cholesterol comes from animal products, such as meat, milk, cheese, and butter.
What Are the Types of Cholesterol?
Cholesterol and fat are transported through the bloodstream in particles called
lipoproteins. Lipoproteins contain different proportions of lipid (fat) and protein molecules:
- Low Density Lipoproteins (LDLs)—LDLs make up most of the body's cholesterol. These particles, called "bad" cholesterol, are partially responsible for forming plaque along blood vessel walls. The more LDLs you have, the greater your risk of getting coronary artery disease—or a
- High Density Lipoproteins (HDLs)—HDLs are known as "good" cholesterol. They are the protective counterparts to LDLs. HDLs contain a high proportion of protein, and their function is to scour the bloodstream, collecting excess cholesterol and transporting it back to the liver.
The liver removes the cholesterol from the body. High levels of HDL cholesterol reduce the risk of heart disease and stroke.
Cholesterol and Heart Disease
Increased levels of cholesterol in the blood can contribute to
atherosclerosis. This is the gradual build-up of cholesterol, fat, and fibrous debris along the walls of your arteries. This plaque build-up can accumulate enough to narrow the artery and stiffen the arterial wall. If the plaque is severe enough it can impair blood flow past the blockage.
Part of the plaque can also break off. Or, the plaque can become unstable and rupture. When this occurs, blood is exposed to the inner material of the plaque, which causes a clot to form. This can can form rapidly and completely obstruct an entire artery, or it can be released into the circulation. Once released, clots can travel through the bloodstream through smaller and smaller vessels until they either dissolve or reach a point where they cannot squeeze through, causing a blockage. When this blockage occurs in a coronary artery (one of several arteries that supplies the heart tissue with blood), the result is often a heart attack. If the blockage occurs in a brain artery, a stroke takes place. The extent of the damage depends on the size of the blood vessel that is blocked or the location of the blood vessel.
What Is Your Risk?
A high level of blood cholesterol is associated with an increased risk of heart disease. However, unlike other risk factors for heart disease that you cannot change or modify, such as age, sex, or a family history of heart disease, you can lower a high cholesterol level. That is why it is monitored so closely.
Check the risk factors below to see if they apply to you. The more risk factors you have, the greater your chances of developing heart disease.
What Are Your Numbers?
Cholesterol levels can be measured with a simple blood test. The table below shows the ranges that have been defined as "desirable," "borderline," and "high risk" for total cholesterol and the different types of cholesterol particles.
If you have had your cholesterol measured recently, see how it compares to the assessments below. Remember that the categories of “desirable,” “borderline,” and “high risk” apply to people at average risk for heart disease and may not be appropriate for you. Your doctor can help assess the degree of risk associated with your particular cholesterol values:
|Lab Test||Desirable||Borderline||High Risk|
|Total Cholesterol||less than 200 mg/dL (5.2 mmol/L)||200-239 mg/dL (5.2-6.1 mmol/L)||more than 240 mg/dL (6.2 mmol/L)|
|LDL Cholesterol||less than 100 mg/dL (2.6 mmol/L)||130-159 mg/dL (3.4-4.0 mmol/L)||more than 160 mg/dL (4.1 mmol/L)|
|HDL Cholesterol||More than 60 mg/dL (1.6 mmol/L)||n/a||less than 40 mg/dL (1 mmol/L) for men and less than 50 mg/dL (1.3 mmol/L) for women|
|Triglycerides||less than 100 mg/dL (2.6 mmol/L)||150-199 mg/dL (1.7-2.2 mmol/L)||more than 200 mg/dL (2.3 mmol/L)|
Ways to Lower Cholesterol
The most effective ways to lower cholesterol and reduce your risk of heart disease include exercising, eating a healthy diet, and taking cholesterol-lowering medicine if you need them. Make sure to have your cholesterol levels tested regularly (once every five years), and do not smoke. If you are concerned about your cholesterol levels, talk to your doctor to create a plan that is right for you.
High cholesterol: understand your risks. Centers for Disease Control and Prevention website. Available at: http://www.cdc.gov/cholesterol/index.htm. Updated July 10, 2012. Accessed September 17, 2012.
Hypercholesterolemia. EBSCO DynaMed website. Available at: http://www.ebscohost.com/dynamed/. Updated September 9, 2012. Accessed September 17, 2012.
NCEP ATP III guidelines. EBSCO DynaMed website. Available at: http://www.ebscohost.com/dynamed/. Accessed September 17, 2012.
What is cholesterol? National Heart Lung and Blood Institute website. Available at: http://www.nhlbi.nih.gov/health/health-topics/topics/hbc/. Updated July 1, 2011. Accessed September 17, 2012.
What your cholesterol levels mean. American Heart Association website. Available at: http://www.heart.org/HEARTORG/Conditions/Cholesterol/AboutCholesterol/What-Your-Cholesterol-Levels-Mean_UCM_305562_Article.jsp. Updated August 23, 2012. Accessed September 17, 2012.
Last reviewed September 2012 by Brian Randall, MD
Please be aware that this information is provided to supplement the care provided by your physician. It is neither intended nor implied to be a substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with any questions you may have regarding a medical condition.
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